With such steam turbines, the bearing struts are located directly in the exhaust steam mass flow. FIG. 4 shows a cross-sectional view of a load-carrying bearing strut 18 which is known from the prior art. This is constructed as a solid body, and has holes 34 for internal location of supply lines, such as seal-steam supply lines. Only a small clearance is provided between the supply lines and the bearing strut 18, for which reason an internal heat transfer takes place between the supply lines, especially seal-steam lines, and the bearing strut 18. Also, a heat input onto the bearing strut 18 takes place from outside as a result of the direct impingement with turbine exhaust steam. The temperature of the exhaust steam mass flow can vary greatly, depending upon operating point, as a result of which the deformation behavior of the bearing strut 18 is directly influenced. The bearing strut arrangements which are known in the prior art, therefore, are sensitive to temperature influences from inside and from outside. In the prior art, therefore, seal-steam temperatures are limited to values of below 150° C., and also large radial clearances are provided between the bearing struts and the exhaust steam casing or the shaft bearing.
An object upon which the present invention is based is to enhance a steam turbine of the type mentioned in the introduction to the effect that thermodynamic efficiency advantages for the entire turbine result.